1. Field of the Invention
The present invention relates to imaging systems and, more particularly, to an infrared (IR) imaging system that can prevent an IR image sensor therein from being affected by visible light.
2. Description of Related Art
The wavelength of IR light is longer than that of visible light. IR light shares many of the properties of visible light, but its different wavelength has several unique characteristics. For instance, materials that are opaque to visible light may be transparent to IR, and vice-versa. IR light is much less subject to scattering and absorption by smoke or dust than visible light, and IR light cannot be seen by the human eye.
Also, unlike visible light, which is given off by ordinary objects only at very high temperatures, IR energy is emitted by all objects at ordinary temperatures higher than 0° K. This means that IR energy is all around us all the time, even in the dark. Different objects give off varying amounts of IR energy, depending on the temperature of the object and their emissivity. Passive IR cameras are designed to sense differing amounts of IR energy coming from the various areas of a scene using an IR image sensor to convert them to corresponding intensities of visible light by electronics for display purposes. This permits true see-in-the-dark capability as well as the ability to observe thermal properties in all light conditions. The IR image sensor can also react to some visible light which will reduces a signal-to-noise ratio of imaging system.
What is needed, therefore, is an IR imaging system which can prevent IR image sensor from being affected by visible light.